Maurice valentine hitt



' a solution is full, clear,

UNITED STATES PATENT OFFICE.

MAURICE VALENTINE HITT, OF PARLIN,

NEW JERSEY, ASSIGNOR TO E. I. DU PONT DE NEMOUBS AND COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE.

SOLVENT FOR. PYROXYLIN BODIES.

1,321,634. No Drawing. Application filed December 10, 1917,

Specification of Letters Patent.

Patented Nov. 11, 1919.

Serial No. 206,439. Renewed June 24, 1919. Serial No.

and in the State of New Jersey, have in-' vented a certain new and useful Improvement in Solvents for Pyroxylin'Bodies; and I do hereby declare that the following is. a

and exact description thereof. The object of my inventionis to provi e a solvent for pyroxylin bodies, havingithe qualities of being cheap, of high solvent power, of bein free from precipitation'of pyroxylin, nonygroscopic, adapted to form a very fluid but cohesive solution, and of,

pleasant odor. A further object is to use a solvent composition containing constituents, which have approximately the same vapor tension, as it-is desirable to have a number of the constituents evaporate more or less simultaneously. A further object is to provide a solvent composition which by reason of the presence of-the alcohol therein can be regulated as to its fluidity by varying the quantity of the alcohol as compared with the quantity of solid constituents therein.

In the pyroxylin industries such as in the manufacture of lacquers, artificial leather, varnishes, etc., there is a demand for a solvent having the above stated qualities.

None of the ordinary lpyroxylin solvents,

such as glacial acetic acid, amyl acetate, and acetone including their homologues and derivatives, has all of these properties in the highest degree, except perhaps amyl acetate,

the price of whih is prohibitive. In these several industri s, it is desirable to vary the relative proportions of the solvent and pyroxy in to obtain a solution of the strength desired, according to the nature of a the pyr'oxylin film to be found. For ex-" ample, in lacquer'work, the solution ordinarily does not contain over five ounces of pyroxylin per gallon in orderthat a "film of proper thickness may be deposited. In some of the decorative arts, a very heavy film is employed which can be deposited from a solution containing as high as twenty ounces of pyroxylin pergallon. There is a strength of solubest adapted thereto, Where desired having less 'pyroxylin than the total amount which the solvent is capable of taking up (for instance, ifa solutlon of twenty ounces of pyroxylin to a tion which is "the following: When,

methyl alcohol having gallon of solvent were desired, which is less than the total amount which the solvent would take up),.it is unnecessary to have the entire quantity of solution composed of pure solvent, it only being necessary to have enough solvent present to dissolve the desired amount of pyroxylin. For economy,

, therefore, it. is customary to add cheap dilucuts to the solvent, which diluents are either entirely non-solvent or nearly so.

The use of diluents,

however, introduces dlficulties, among which may be mentioned as used in a factory, these solvents are evaporated at the ordinary room atmosphere in order to deposit a film of pyroxylin, there is a tendency, except in the case of those solvents which-are nonhygroscopic but expensive such as amyl acetate, toward a separation out of the nitrocellulose or other solvents through absorption ofmoisture from the air or through the change in the composition of the solvent mixture resulting from the-unequal rate of evaporation of its components, this precipitation-being usually evidenced by the appearance of a whitish substance,- technically known as blushing or blooming? or b the settling to the bottom of a ]ellylike mass. Such separation tends 'to decrease the strength of the film and, in somecases, the white appearance produces ob ect1onable color efi'ects:

I have discovered that by using a mixture of ethyl acetate and ethyl or methyl alcohol as the solvent and benzol as the diluent (with or without other components), a mmmm is obtained which has a maximum solvent power and in which there is no tend-- solvent ethyl acetate, is retained so that the mixture inay containas high as seventy per cent., or even more, of benzol. I find that during evaporation under ordinary factory conditions, the ethyl acetate, ethyl or methyl alcohol and benzol mixture deposits a film 'which is strong and transparent. For example, my invention may be carried out by using a solvent comprised of 41 parts by weight of ethyl acetate, 50 parts by weight of benzol, and 9 parts by weight of ethyl or dissolved therein a.

quantity of nitrocellulose in the proportion oftwo pounds. of nitrocellulose to seven pounds of the solvent mixture. But the relative percentages of these ingredients may vary widely according to the'conditionscovering' the i1mumerabl euses to which. the

' solution may be put. I have given specific apparatus which is large, and there is a tend-' instances merely by way of illustration, and am not to be confined to the particular proportions given, as they-are to be regarded as typical only. An increase in the benzol component results in reduced cost, and its disadvantage lies in the less rapid solvent action which such a-mixture possesses. The

place of ethyl alcohol, I may use anothervolatile saturated aliphatic alcohol such, for

example, as methyl alcohol.

As the boiling points of the liquid pen.

stituents are in the same neighborhood, it is not necessary to raise the temperature of any one much above another in order to secure evaporation of the solvent portion of the solution. This has the advantage that the vapor tension of no one of the evaporating constituents is higher than is necessary to produce evaporationof that particular constituent. This low vapor tension in evaporation isvery desirable since the evaporation usually takes placewithin an ency for the vapor to escape from the apparatus if the vapor tension is at all high.

I find that my mixture is'comparatively non-hygroscopic,.which is a very desirable quality, since the absorptionof water'in such a solution results in a precipitation of the pyroxylin. I

I find also that the presence of the alcohol causes the benzol'to be evaporated earlier than would otherwise be the case. In the evaporation of the solvent composition the alcohol, benzol and ethyl acetate would first evaporate together until the alcohol has substantially entirely evaporated, thereafter the benzol and ethyl acetate would evaporate have hereunto set my hand.

together until all of the benzol has evaporated and finally only eth l acetate would be left. By the presence 0 the alcoholthe residue of ethyl acetate is obtained more quickly as the benzol evaporates more quickly than if the alcohol were not present.

While I have described my invention above in detail,I wish it to be understood that many changes may be made therein without departing from the spirit of my invention.

I claim:

1. A pyroxylin solvent comprising a mixture of ethyl acetate, a lower member of the benzene series of hydrocarbons, and a saturated aliphatic alcohol whose rate of evaporation is somewhat similar to that of the other constituents.

2. A pyroxylin solvent comprising a mixture of ethyl acetate, benzol, and a saturated aliphatic alcohol whose rate of evaporation is somewhatsimilar to that of the other constituents. i

. 3. A pyroxylin solvent comprising a mixture of ethyl acetate, a lower member of the benzene series of hydrocarbons and ethyl alcohol.

4. A pyroxylin solvent comprising a mixture of ethyl acetate, benzol and ethyl alcohol.

5. A pyroxylin solvent comprising a mixture. of ethyl acetate, :1, lower member of the benzene series of hydrocarbons, and a constituent adapted to rapidly evaporate the benzene hydrocarbon.

6. A pyroxylin solvent comprising a mixture of ethyl acetate, benzol and a volatile constituent adapted to rapidly evaporate the benzene hydrocarbon.

7. A pyroxylin solvent comprising a mixture of ethyl acetate, a lower member of the benzene series of hydrocarbons, and a volatile constituent adapted to rapidly evaporate the benzene hydrocarbon having substantially the same vapor tension as the other solvent constituents.

8. A pyroxyl' ""solvent comprising a mixture of ethyl acetate, benzol and a volatile constituent adapted to rapidly evaporate the benzene hydrocarbon having substantially the same vapor tension as the other solvent constituents. v

In testimony that I claim the foregoing I MAURICE Witnesses:

F. L. FULLAM, G. B. FREEMAN.

YALENTINE HITT. 

